Ball valves are extensively utilized. A packing, which is clamped between the valve housing and the pivot shaft in the area of the lead opening of the valve housing, is used in these conventional ball valves as a sealing system. The packing is dynamically loaded through the pivoting of the valve shaft during opening and closing of the ball valve and is therefore subjected to wear. Leakage can occur during wear. Such leakage can be most undesirable and dangerous if environmentally damaging fluids are guided through the valve.
A ball valve was introduced at the 1988 Achema show in which the sealing system is designed with a base ring which is statically sealed off on the valve housing and which surrounds the pivot shaft; a bellows, which rises above said base ring away from the flow axis, is connected fixed against rotation and tightly to the base ring and surrounds the pivot shaft; a bellows end ring, which is connected fixed against rotation and tightly to the bellows on its end which is remote from the flow axis, surrounds the pivot shaft; a first sliding packing ring, which is attached fixed against rotation and tightly to the bellows end ring, surrounds the pivot shaft and is on the side of the valve housing; and a second sliding packing ring, which is connected fixed against rotation and tightly to the pivot shaft, surrounds the pivot shaft and said two sliding packing rings rest sealingly and slidingly against one another under a sealing pressure produced in particular by the bellows. The sliding packing ring is thereby mounted tightly and fixed against rotation on a cap, which is closed off tightly and grips over the end of the pivot shaft, which end is with respect to the flow axis the radial outer end of the pivot axis, and said cap is screwed to the pivot shaft and is secured against an unintended rotation.
A purpose of the invention is to more reliably design the screwed lock between the pivot shaft and the cap while simultaneously maintaining the seal.
To attain this purpose, the invention suggests that the cap has an opening which, at its end which is remote from the flow axis, is tightly closed off by a removable cap lid, and wherein a releasable locking means are positionable within the cap and, with the cap lid secured to the cap, the locking means secure the cap against screwing (i.e. rotation) relative to the pivot shaft. Working surfaces for engagement by a tool are provided on the cap or on the cap lid.
An easy access to the locking means is assured in the construction of the invention in that only the cap lid needs to be released in order to make said locking means accessible.
According to an embodiment, which is particularly advantageous for installation purposes, the locking means are formed by a fork member with fork legs, which rest on flat portions of the pivot shaft, which fork member is constructed fixedly in particular in one piece with the cap lid, with the cap lid being fixedly and sealingly secured on the cap.
According to another embodiment, the locking means includes at least one key received in a keyway inside of the cap, with said key resting at the same time on a flat portion of the pivot shaft.
The cap lid can be secured on the cap by fastening screws. To seal off the space within the cap, a flat gasket ring is arranged between the cap and the cap lid.